U.S. Pat. No. 5,343,944, issued Sep. 6, 1994; U.S. Pat. No. 5,538,080 issued Jul. 23, 1996 and U.S. Pat. No. 5,636,688 issued Jun. 10, 1997, all to Grey Bassinger, disclose and claim self-aligning stuffing boxes for use in sealing the reciprocating pump rod or so-called "polished rod" of well pumping units. The subject matter of these patents is hereby incorporated herein by reference.
Each of the above referenced patents discloses and claims a self-aligning stuffing box assembly which allows a rod packing or seal means to move laterally with respect to the central axis of the stuffing box housing and thereby accommodate some lateral displacement of the pump rod. However, there is still a tendency to wear the packing or seal means generally at the point where the packing or seal holder is being biased in a particular direction with respect to the central axis. Accordingly, the seal means or packing tends to wear unevenly and begin leaking due to the lateral deflection of the rod.
A related problem in assembling the stuffing box and packing assembly or when replacing the polished rod packing, is the difficulty encountered in properly aligning the polished rod with respect to the stuffing box before placing the pumping unit in service. It is often difficult and time-consuming to measure misalignment and adjust the position of the pumping unit with respect to the common central axis of the tubing string, wellhead and stuffing box housing. In this regard it is desirable to provide means which could be used to assist in aligning the polished rod with regard to structure including the stuffing box housing or frame which is already mounted on the wellhead.
The foregoing problems in the art of stuffing boxes for reciprocating pump units have been solved by the present invention.